The international standards, such as, for example, DIN 51 780 (outdated), (EN) ISO 7536 or ASTM D 525, exist for the determination of the oxidation period, for example, of fuels. These standards stipulate that a 50 ml fuel specimen is placed and sealed in a pressure vessel with specified deviations, and is charged with oxygen to a pressure of 700 kPa so as to determine the time of the pressure drop setting-in later on, which presents the standardized oxidation result.
Conventionally, a device for an accelerated oxidation test of fuels and petroleum products is provided with a pressure gauge, and is placed in a water bath tempered at 100° C. Under these conditions (increased temperature, as well as oxygen under pressure effect), the fuel usually oxidizes considerably faster than under normal storage, which allows conclusions to be drawn regarding the lifespan of the fuel expected under normal ambient conditions in this regard.
The manual or automatic evaluation takes place on the basis of the oxidation that sets in after some time, which, according to the standards, is defined as the breaking point with 14 kPa pressure drop in 15 minutes, and in automatic detection, leads to the recording of curves/data.
In case of present day fuels, the breaking points, under the above mentioned test conditions, typically lie around 6 . . . 8 hours, which has to be felt as very disadvantageous, if one compares these periods with those of the other laboratory tests for the dispatch release, which are mostly made within minutes. Furthermore, there are fuels, whose additives decelerate the oxidation in such a manner that the slope described in the standard ASTM D 525 for the result sought is not achieved.
Thermal processes are applied as additional techniques, such as, for example, the dynamic Heat Flux or the dynamic Differential Scanning Calorimetry (DSC), and/or the Pressure Differential Calorimetry (PDSC) in which the heat flux of a small sample quantity is determined under defined measuring conditions. Thereby, a local temperature increase in the specimen compared with the environment indicates an oxidation.
Consequently, the problem of the invention was to provide a method and a device for an accelerated oxidation test of fuels or petroleum products, as well as a computer program to control such a device, and a corresponding computer readable storage medium, which eliminate the above mentioned deficiencies and, in particular, allow to reduce the time duration for the determination of the breaking point.